Dental furnace.



PATENTED APEQ18, 1905.

I A. E. MATTESON.

DENTAL FURNACE APPLIOATION FILED SEPT. 19,1904

4 SHEETS-SHEET 2.

PATENTED APR. 18, 1905.

A. E. MATTESON. DENTAL FURNACE.

APPLIOATION FILED SEPT. 19.1904.

4 SHEETS-SHEET 3.

No. 787,584. PATENTED APR. 18, 1905.

A. B. MATTESON.

DENTAL FURNACE.

APPLICATION FILED SEPT. 19,1904.

4 SHEETS-SHEET 4.

UNITED STATES Patented April 18, 1905,

PATENT OEEIcE.

DENTAL FURNACE.

SPECIFICATION forming part; of Letters Patent No. 787,584, dated April 18, 1905.

Application filed September 19, 1904.. Serial No. 225,040.

1'0 all LU/7,7177% it Ina/y concern.-

Be it known that I, ARTHUR E. MATTEsoN, of Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Dental Furnaces, of which the following is a specification.

This invention relates to dental furnaces, and more particularly to an electric furnace adapted for use in the manufacture of artificial teeth, bridgework, gums, and the like and in which a high degree of heat is required Among the salient objects of the invention are to provide in a furnace of the character referred to such improvements in construction and arrangement that the winding of the resistance or heat-conductor upon the muflie thereof can be easily and accurately done and so distributed over the muffle as to produce an equable heat within the oven and in such a manner that it is unaffected by the contraction and expansion due to the extreme changes in thetemperature to provide a furnace the muffle of which is removable for inspection and repairs and the investment or insulation about the winding of which as readily removed, whereby the winding can be quickly and easily repaired or an entirely new winding applied thereto, thus greatly facilitating the matter of repairs; to provide a closure for a furnace of the character referred to having a heat-conductor wound thereupon, whereby it becomes a heat-wall as well as a closure for the furnace; to provide such connections between said muffle and closure and the electric supply that the portions of the conductor running to the muffie and the closure therefor is connected in multiple; to provide an end member for the furnace-body which forms the casing to tional view taken on line 2 2 of Fig. 1. Fig. 3 is a sectional view taken 011 line 3 3, Fig. 4. Fig. 4 is a side elevation of the furnace. Fig. 5 is an inside elevation of the closure for said furnace. Fig. 6 is an edge view of the same. Fig. 7 is a detail view showing the inner plate thereof. Figs. 8 and 9 are perspective and rear end views, respectively, of a muffle for the furnace. Figs. 10, 11, and 12 are front, side, and rear end elevations, respectively, of another form of muffle for said furnace. Figs 13, 14, 15, and 16 are front, plan, rear end, and side elevations of still another form. of muffle and Fig. 17 is a diagrammatic view of the winding.

Referring to the drawings, 1 designates as a whole the furnace-body or outer casing, made of slabs of soapstone, porcelain, iron, or other suitable material, secured together in box form by means of screws or otherwise and provided on its under side with short supporting-legs 2, one side of said casing being provided with an opening thcrcinto with a closure 3, having a beveled portion fitted to a correspondingly-formed casing around said opening. I have discovered by extensive experiments that soapstone possesses peculiar qualities for the manufacture of such furnaces, and particularly for use as the member of the outer casing of the furnace forming the closure-casing, for the reason that it expands and contracts a very little as compared with other materials which have been heretofore used in the manufacture of such furnaces, and enables me to provide a closure for the furnace which fits accurately and which is not affected in the performance of its function by the very slight expansion or contraction. The closure-casing is preferably made bevel as to its inner edge and the edge of the door or closure fitted thereto, whereby any variation in the corresponding size of the opening in the casing and the fitting edge of the closure is provided for by the outward or inward movement of the closure, thus always retaining an effective fit of the closure to the casing without binding or breaking.

4 designates a muffle of shell-like construction, made of thin porcelain or other suitable refractory material and having one end open, as clearly indicated in Fig. 8, said opening being arranged to register with the opening into said outer casing or furnace-body when the muffle is in place, as shown in Fig. 2. The outer surface of said muffle is provided with a series of slightly-undercut lugs or studs 5, distributed thereupon adjacent the front edge and upon the rear end thereof, as shown in Figs. 8 and 9 and also in the modified forms shown in Figs. 10 to 16. Upon these lugs or studs, passing from one to another, is Wound an electric-current conductor 6, the ends of said conductor terminating in the form shown in Figs. 8 and 9 at the front lower corners of the muffle, as seen in Fig. 8. After the conductor or heating medium has been thus wound upon the muffle an outer coating or covering 7, composed, preferably, of sileX mixed with gum-arabic and water, is applied thereto, The object of this coating is to assist in holding the laps of the winding in proper relation to each other and insulate them from each other and from any foreign substance used in the manufacture of the furnace which would fuse if ongaged by the wire and cause damage to the winding or, perhaps, short-circuit the same. This coating is comparatively thin, and by using the ingredients mentioned the winding is properly insulated during the assembling of the furnace, and after the electric current is passed through the conductor the coating loses its cohesive properties and is easily removed or brushed from around the winding when the muffle is removed from the furnace for repairs. The old winding is thus readily exposed for repair or can be removed and a new conductor wound in its place and a fresh coating of sileX, gum-arabic, and water applied thereto as before. Another advantage in using a matter which loses its cohesive properties when heated is the fact that the winding is free to respond to changes in temperature, the laps of the conductor being free to move through. the coating under contraction or expansion.

The edge of the muffle around the opening projects slightly beyond the series of lugs mounted thereupon and 'forms a shoulderlike portion, (designated 4.) Said shoulder is adapted to fit into the opening to the furnace-body when said muffle is placed within said body, whereby the opening to said muffle registers with the opening to said furnacebody, as indicated in Fig. 2. Assuming that the rear end wall of the furnace-body is removed and the muffle put into place, a filling or packing 7 is placed around the muffle. This filling is preferably of hard-coal ashes and forms an insulation between the heated muffle and the outer walls of the furnacebody, thus preventing the furnace-body from being much. heated and retaining the heat around the muffle. Any other suitable matl l l l ter might be employed for a filling with the same result.

8 and 9 designate a pair of cars or lugs upon the front edge of the side slabs of the outer casing provided, respectively, with bearingapertures 8 and 9, adapted to receive the ends of a hinge-bar 10 upon the lower side of the door or closure 3.

11 designates a pair of end caps mounted upon the ends of the bar 10 and forming contact-points through the openings 8 and 9, against which spring contact-arms 12 bear, said arms 12 being mounted upon opposite sides of said furnace-body and connected with the electric-current conductor 6 from the nmffle-winding, hereinbefore referred to.

The door or closure 3 is of shell-like construction, having therein a chamber 13 filled with hard-coal ashes or other suitable insu lating matter. The inner plate 14 of said door or closure is of the same material as the muffle 4 and is also provided on its side toward the chamber 13 with a plurality of lugs 15, upon which are wound, passing from one to another, an electric-current conductor 16, the ends of said conductor terminating at and connected with the caps 11.

1.7 designates a peep-opening through the door 3 into the interior of the furnace, and 18 a spring adjustably mounted upon the furnace-body and projecting downwardly against the closure 3 to hold. it closed.

The electric-current conductor or winding leads from the furnace-muffle through the rear of the body or outer casing of the furnace, as indicated at 18, Fig. 2, through suitable openings prepared for that purpose and is connected with any suitable source of electric supply, as a dynan'lo A, diagrammatically shown in Fig. 17. The strength of the current supplied to said conductor for heating the muffle and the closure is regulated by a rheostat of any well-knmvn type and diagrammatically shown in Fig. 17 and designated B.

From the above description and the diagrammatic View in Fig. 17 it will be understood that the winding of the nmflle and of the closure is arranged in multiple, one part of which balances, as it were, the other part that is to say, the current flows out from the dynamo A to the left through the rheostat B to the point C. At this point the current divides, a portion of it passing upwardly through the conductor 6, representing the winding of the muffle, to the point f), and the other portion passing downwardly through the contact-arm 12, the cap 11, and through the conductor 16, representing the winding upon the closure of the furnace,thence th rough the cap and arm 11 and 12, respectively, at the opposite side of the figure and through the conductor 6 to the point D, where it joins the first portion of the original current, and the full current returns to the dynamo A through the conductor, (designated E,) it being understood that the connection at the point D is so placed that the two portions of the current divided at C balance each other in the resistance encountered during the course of travel to the meeting-point at D. By this construction the closure of the furnace is made a heating-wall of the furnace, as well as performing its function as a closure therefor, and the heat derived from such winding is uniformly distributed over the muffle and closure therefor. It is also possible to connect two or more furnaces in series by using muffies like the one shown in Figs. 10, 11, and 12, wherein two terminals are provided at the rear of the muffle adapted to be connected with the adjacent muffle of the se ries.

Referring to Figs. 13 to 16, inclusive, a smaller muffle is here shown, and the winding is such that the greatest amount of heat is generated near the open end of the muffle, thus malging it possible to do away with a heated closure for small muffles. It will be observed that the winding is very close upon the edge of the muflie and that the laps extend backwardly toward the rear end of the muffle at various distances. This can be regulated as desired and so distributed over the surface of the muffle that all parts of the muffle will be evemy heated. By the use of the lugs or studs distributed over the surface of the muffie to receive the winding the winding can be so distributed that an equable heat can be secured within the muffle and parts which are usually underheated can be provided with a greater number of laps of the winding, while parts or portions of the muffle which are usually overheated can be supplied with fewer laps of the winding, thus making a very useful and effective means for applying the winding to the muffle and so distributing the winding and holding each lap thereof that the expansion and contraction due to the extreme changes in temperature do not in any manner affect the uniformity and efficiency of the furnace. The closure for the furnace is constructed in the same general way that the walls of the furnacebody and muffle are constructed and arranged. The inner plate of the closure being of the same material as the muffle is provided with awinding of heat-conductor and covered with the coating of insulating substance in the same manner as the muflieis. It is also provided with the heat-insulating filling of hard coal ashes, thus producing a furnace having heating-walls entirely surrounding the mufflechamber.

VVhile I have herein shown and described what I deem the preferred embodiment of the invention, it is obvious that alterations and modifications can be made in the details of construction and arrangement without departing from the spirit of the invention, and I do not, therefore, limit the invention to the forms herein shown and described, except in so far as the details thereof are made the subject-matter of specific claims.

I claim 1. In a dental furnace, a muffie provided upon its surface with a plurality of projecting holding members and adapted to have wound thereupon from one to the other a heat-conductor for said furnace.

2. In a dental furnace, a muffle provided with a plurality of lugs distributed over the surface thereof and adapted to have attached thereto a heat-conductor passed from one lug to another over the surface of said muffle, for the purpose described.

3. In a dental furnace, a muffle provided on its exterior surface with a plurality of undercut lugs distributed over said surface and adapted to have an electric-current conductor attached thereto, and a conductor pass ing from one lug to another over the surface of said muffle, substantially as and for the purpose described.

4. In a dental furnace a muffle having one side open and provided with a plurality of holding members closely distributed thereupon around said opening, other holding members distributed over the body of said muffle toward the rear end thereof, and a heat-conductor wound upon said holding members, substantially as described.

5. In a dental furnace, a furnace-body or outer casing having an opening at one side thereof, a muffle mounted within said outer casing and having an opening in register with the opening into said outer casing, a clo sure for said openings, an electric-current conductor applied to said muffie and to said closure for heating the same, and a coating of insulating matter rendered friable by heat applied to said muffle and closure and cover ing said conductor, that part of the conductor running to the closure and to the muffle being connected in multiple, substantially as described.

6. In a dental furnace, a furnace-body or outer casing having an opening at one side thereof, a muffle mounted within said outer casing and having an opening in register with the opening into said outer casing, a plurality of holding members mounted upon the surface of said muffle and adapted to have attached thereto an electric-current conductor, a closure for said furnace, said closure also provided with a plurality of holding members adapted to have applied thereto an electric-current conductor, and an electric-current conductor applied to said mufile and to said closure for heating the same, those parts of said conductor running to said closure and to said muffle being connected in multiple, substantially as described.

7. In a dental furnace, an outer casing, a muffle of thin refractory material mounted within said outer casing and provided with a plurality of holding members distributed thereupon and adapted to have attached thereto a heat-conductor, a closure for said furnace, and a heat-conductor applied to said holding members and passing from one to another over the surface of the muffle, for the purpose described.

8. In a dental furnace, an outer casing, a muffle of thin refractory material mounted Within said outer casing and provided with a plurality of holding members distributed thereupon and adapted to have attached thereto a heating medium, a heating medium applied to said holding members, a coating of insulating matter applied to said muffle over said holding members and said heating medium, and a closure for said furnace, substantially as described.

9. In a dental furnace, an outer casing, a muffle of thin refractory material mounted within said outer casing and provided with a plurality of holding-lugs distributed over the surface thereof and adapted to have attached thereto an electric-currentconductor, a conductor applied to said lugs, passing from one to the other over the surface of said muffle, a coating of insulating matter applied to said muffle over said lugs and said conductor, a filling of hard-coal ashes or analogous matter between the interior of the outer casing and the muffle, and a closure for said muffle and outer casing, substantially as described.

10. In a dental furnace, an outer casing, a muffle of comparatively thin refractory material mounted within said casing and provided with an electric-current conductor Wound thereupon, a coating of insulating matter applied over said conductor and rendered friable, a closure for said furnace also provided with an electric-current conductor and a coating of insulating matter over said conductor, and electric connections between said closure and said muffle-winding, whereby to simultaneously heat said muffle and said closure by passing electric current through said conductor, substantially as described.

11. In a dental furnace, a muffle therefor provided with a heat-conductor wound thereupon, and an insulating matter applied thereto over said conductor, said insulating matter comprising a cohesive mass of mortarlike substance deprived of its cohesive properties under the influence of heat.

12. In a dental furnace, a muffle therefor provided with a heat-conductor wound thereupon, and an insulating substance applied thereto over said conductor, said insulating substance comprising a mixture of silex, gum-arabic and water, or an analogous mixture, substantially as and for the purpose described.

13. A furnace of the character referred to having a wall of material substantially nonexp ansible under the influence of heat and provided with a beveled opening therethrough, and a closure therefor having a correspondingly-beveled edge fitting the inner edge of said opening, whereby said closure as it expands under the influence of heat moves outwardly upon the beveled edge of said opening without binding or causing an opening between the edges of said closure and said wall, substantially as described.

14:. In a dental furnace, an outer casing or furnace-body of box-like construction provided with an opening in one side thereof, a closure hinged upon said furnace-body, the hinges of which constitute contactpoints, contact-arms mounted upon ,said furnacebody and engaging said hinge contact-points, a heat-conductor applied to said closure and connected with said contact-points, a muffle mounted Within said furnace-body and provided thereupon with a heat-conductor connected with said contact-arms, and an insulating-filling within said furnace-body around said muffle, substantially as and for the purpose described.

15. In a dental furnace, a furnace-body composed of refractory material, a muffle removably mounted therein, a heat-conductor wound upon said muffle, an insulating-filling around said muffle within said furnace-body, a closure for said furnace-body provided with a heat-conductor and having a chamber therein adapted to be filled with heat-insulating substance, and electric connections between said muffle and said closure, whereby said conductor is connected in multiple to said muffle and said closure, substantially as described.

ARTHUR 1E. iNI'ATI [CSO N Witnesses:

VVM. R. LIIZENBERG, FREDERICK O. Goonwm. 

